The 33-14 vote came after the mayor made changes to the camera plan in an effort to build support among aldermen leery of backing a package that some of their constituents view as a cash grab by the city.

Ald. James Balcer, 11th, spoke with emotion, describing how he “was hit by a car and almost killed” in 1958 when he was 8 years old. “I still see the bumper of the car hitting me, the pipes passing over me, trying to get up, falling into the man’s arms,” he said. “It was a traumatic experience in my life.”

“The safety cameras are good. They’re good for our communities,” he added. “They will save lives, not only of our children, but the elderly, the disabled, the infirm. . . . If people don’t want a ticket, obey the law. Drive the speed limit.”

The Tribune reported last month that the Emanuel administration's research it used to push the speed-camera ordinance was error-ridden.

The newspaper's analysis of city traffic data provided to the federal government led to a very different and less dramatic conclusion.

Instead of the 60 percent reduction the mayor touted, the Tribune's analysis of accidents for the same locations revealed a nearly 26 percent reduction -- one that mirrored a broader accident trend in the city and across the nation. The difference? The city said fatalities dropped from 53 to 21 in the targeted zones, but the federal statistics showed the before-and-after numbers were 47 and 35.

Presented with that conclusion last month, the Emanuel administration week reversed course and said its initial statistical summary was error-ridden and shouldn't have been provided in the first place.

Ald. Leslie Hairston, 5th, questioned the administraton's research and said aldermen would not get a say in location of speed cameras. Hairston said she'll be voting no.

Last week, the mayor tweaked the ordinance reducing the fine for driving six to 10 mph over the limit in a speed camera zone from $50 to $35. The fine for going 11 mph or more over the limit will be $100.

The cameras would operate near schools from 7 a.m. to 7 p.m. Monday through Friday and while parks are open.

Emanuel sought to ease concerns about the potentially wide reach of his proposal by casting it as a "safety zone" plan with a limited number of cameras.

Both the state law and Emanuel’s ordinance permit speed cameras within one-eighth of a mile of the city's parks and public and private schools, which would allow the administration to cover nearly half the city with speed cameras, based on a Tribune analysis.

In seeking more support, the administration focused on the legal definition of those zones, many of which overlap. That has allowed the administration to say it will put cameras in "no more than 20 percent of all eligible safety zones shall be equipped" with speed cameras.

What the ordinance doesn't point out is that there are many places where three, four or even five schools and parks fall within the same one-eighth-mile radius. While the city took some of those overlapping zones into account, under the approved scenario, it is still possible the mayor's plan could cover nearly half the city.

Aldermen will be notified where the cameras will go in their wards but won't be able to block them. Alderman blanched at the idea of giving up local control. They have long enjoyed wide latitude to approve or deny projects within their wards.

During the first 30 days, only warning tickets would be issued, according to state law. The city included an additional provision that first-time violators will be issued one warning ticket before getting fined.

Red-light cameras generated $69 million for the city in 2010, and speed cameras likely would grow ticket revenue considerably.

The mayor's effort has been supported by the Traffic Safety Coalition, a group pushing for the speed cameras that is run by close Emanuel political ally Greg Goldner and funded by Redflex Traffic Systems, the city's red-light camera vendor.